[OPTICAL REVIEW Vol. 7, No. 4 (2000) 348-352]
Explanation of Human Skin Color by Multiple Linear Regression Analysis Based on the Modified Lambert-Beer Law
Miho SHIMADA,1 Yuji MASUDA,2 Yukio YAMADA,3 Masahide ITOH,1 Motoji TAKAHASHI2 and Toyohiko YATAGAI1
1Institute of Applied Physics, University of Tsukuba, 1-1-1, Ten-noh-dai, Tsukuba, Ibaraki, 305-8573 Japan, 2Shiseido Research Center, 2-12-1 Fukuura, Kanazawa, Yokohama, Kanagawa, 236-8643 Japan, 3Mechanical Engineering Laboratory, 1-2, Namiki, Tsukuba, Ibaraki, 305-3564 Japan
(Received October 13, 1999; Accepted March 24, 2000)
Quantitative analysis of human skin color is needed in the medical and cosmetic fields. Because of the strong light scattering by biological tissues, however, analysis of skin color has not yet been fully successful. Human skin color is dominated by the colors of blood and melanin which are modified by scattering. Exposure of human skin to hot water or UV-ray changes its color because the absorbance spectrum of reflection from the human skin, and the changes in the absorbance spectra of reflection reflect the absorbance spectra of blood and melanin which are the absorption spectrum distorted by scattering. By applying the modified Lambert-Beer law, the absorbance spectrum of reflection from human skin can be expressed proportional to those distorted absorbance spectra of blood and melanin. Multiple linear regression analysis is successfully used to reproduce the absorbance spectrum of reflection from human skin from the distorted absorbance spectra of blood and melanin.
Key words : spectrum analysis, absorbance, optical pathlength, scattering media, regression analysis, skin color